Selective ion exchange resins

ABSTRACT

Ion exchange resins utilized for removing boron or arsenic from aqueous solutions. The resins are especially effective when the solutions contain other dissolved salts, such as sulfates and chlorides, particularly calcium chloride.

D United States Patent 11 1 [111 3,887,460

Ward et al. June 3, 1975 [54] SEIIECTIVE ION EXCHANGE RESINS 2,813,232 llzyman etlal 210/24 3,53 1 an et a 210 37 [751 Invenmrs: chrlsmph" Mm ward; Cynl, 3,803,059 4 1974 Kess ick 260/21 c Alfred Morgan, both of Chadwell Heath; Richard Paul Allen, OTHER PUBLICATIONS Surbiton, all of England Polymer Letters, Phenolic Resins Capable of Boron [73] Assignee: United States Borax & Chemical complexauon 521-530 c p L08 g Chemical Abstracts, VOl. 74, p. 242, Chemical Abstracts, Vol. 74, p. 482, 1971. [22] Filed: June 1, I973 21 App] 3 5,909 Primary Examiner-Samih N. Zaharna Assistant Examiner-Peter A. Hruskoci Arr A t, F J R. Th t 52 U.S. c1. 210/37; 260/2.l c may gen or mm m on [51] Int. Cl C02b l/56 58 Field of Search 210/24, 37, 38; 260/2.1 c, [57] AFSTRACT 2 0 22 C Ion exchange resins utilized for removing boron or arsenic from aqueous solutions. The resins are especially 5 References Cited effective when the solutions contain other dissolved UNITED STATES PATENTS salts, such as sulfates and chlorides, particularly call d 2,104,501 1/1938 Adams et al.. 210/38 mum ch on 6 2,389,865 11/1945 Mills et a1. 260/2.l C 7 Claims, N0 Drawings SELECTIVE ION EXCHANGE RESINS This invention relates to ion-exchange resins and to 1 improved method for the removal of ionic species om aqueous solutions. lon exchange or ion chelation may be defined as the :versible interchange of ionic species between a liquid T1356 and a solid phase (the resin) such that the solid 12156 undergoes no permanent change. An object of the present invention is the provision of 1 ion-exchange resin which is selective for anions or :ids containing boron or arsenic. Most currently availle conventional anion-exchange resins have low sectivity for boron-containing ions which makes their ae impractical in any but pure solutions. It is well known that boric acid and borate ions form rong complexes with dihydroxy compounds having an )propriate steric configuration. It is also known that lCh hydroxy compounds may be successfuly incorpo- .ted into selective ion-exchange media by po1ymeriza on with formaldehyde. However, relative positions of le components of such resins are not necessarily steriilly favorable for interaction with boron species. It has been found that complexes formed from aroatic hydroxy compounds and anions containing bo m, may be used in the formation of a highly selective iion exchange resin by polymerization with, for exam- .e, formaldehyde. Accordingly, this invention prodes a resin formed by the polymerization process beween a suitably pre-formed complex of boron and an 'yl-hydroxy compound and formaldehyde, or a for- .aldehyde generating source together with a suitable 'oss linking agent. Examples of suitable aryLhydroxy )mpounds are phenol, dihydroxybenzenes, trihyroxybenzenes, (and other aryl compounds with meth- 01 groups adjacent to the phenolic group), dihydroxiaphthalenes, and their substituted derivatives, for exnple, salicylic acid and gallic acid. A suitable cross nking agent is resorcinol. Basic catalysts such as solum and ammonium hydroxides and zinc oxide are referably employed. a A particular advantage of this invention is the provion of an ion-receiving site, based on the stereohemistry of the original boron-containing complex, hich is preserved when manufactured duringpolylerization and subsequent removal of initial borate, nd when used, during loading and elution of boron )ecies from the resin. Thus, ion-exchange resins made :cording to this invention will have anion-receiving tes of the same stereo-chemistry as the tetrahedral boate ion. The resins therefore possess improved properes for the specific removal of borate, boric acid and rsenite.

Another feature of the resins, according to the invenon, is that they can be used as an initial block for the roduction of higher molecular weight polymers. The |vention is illustrated by. the following examples.

EXAMPLE I Oriented Salicylic Acid Resins '.0.1 mol.

Salicylic acid 1 .8 g

1 g. 0.05 mol.

3 Boric acid 3.

-Continued Sodium hydroxide 2.0 g. 0.05 mol. Water 25 ml.

The clear solution was mixed with 40 percent w/v formaldehyde solution (36 m1.) and anhydrous sodium acetate (20 g.) was dissolved in this mixture. After heating the solution for 30 minutes at 60C., resorcinol (5.5 g.; 0.05 mol.) was added and dissolved. The resulting mixture was heated and stirred for a further 60 minutes at 60C. when, after becoming increasingly viscous, it set to a resilient, orange-colored gel. The gel was cured for 12 hours at 110C.

Cured resin (33 g.) was ground and screened to 30 100 US. mesh. Boric acid was leached from the resin with hot 10 percent hydrochloric acid. 1.0 g. of the washed resin was converted to the Na form and placed in 150 ml. ofa solution containing 25 mg. B (as borax) at a pH of 9.5. After three days, 1.0 g. of resin was found to have removed 4.2 mg. B from the test solution.

EXAMPLE ll Oriented Gallic Acid Resin The gallic acid-boric acid complex was formed by heating the following mixture until a clear solution was obtained.

Gallic acid 9.4 g. 0.05 mol Boric acid 3.1 g. 0.05 mol. Sodium hydroxide 4 0 g. 0.1 mol. Anhydrous sodium acetate 5.0 g. Water 30 ml.

The solution was mixed with 40 percent w/v formaldehyde solution (8 ml.; 0.11 mol.) and the resulting mixture heated for 40 minutes at 45C. Resorcinol (2.57 g.; 0.025 mol.) was then added. The resulting mixture was heated and stirred for a further minutes, after which it gradually set to a tough wine-red gel. The gel was cured for 16 hours at 90C.

The cured resin was ground and screened to 30 US. mesh. Boric acid was leached from the resin with hot 10 percent hydrochloric acid. 1.0 g. of the washed resin was converted to the Na" form and placed in ml. of a solution containing 25 mg. B (as borax) at a pH of 8.8. After three days, 1.0 g. of resin was found to have removed 6.4 mg. B from the test solution.

EXAMPLE Ill Resin prepared according to Example [I was converted to its Na form.

A solution containing B (as borax) l0 p.p.m. SO, 1800 p.p.m. Cl 600 p.p.m.

was prepared and buffered to pH 9.5, and passed through the resin at a rate of 2 g/min/cu.ft. Collection and analysis of the effluent showed the resin capacity to be 0.35 mg. B/ml.

EXAMPLE IV Resin l.0 g.) prepared according to Example I] was converted to its H form and placed in 200 ml. of a so-- lution containing 50 mg. arsenite (As[lll]) at a pH of 9.5. After three days, 1.0 g. of the resin was found to have removed 8.2 mg. As from the test solution.

EXAMPLE V A control resin (free of B) prepared as in Example II was tested according to Example III. Collection and analysis of the effluent showed the resin capacity to be 0.2 mg. B/ml.

The resins are especially useful for absorbing boroncontaining and arsenic-containing ions from aqueous solutions containing dissolved salts such as sulfates and chlorides, especially salts of metals in Group "A of the Periodic Table, such as calcium. For optimum absorption capacity, the pH of the aqueous solution should be not less than 4.

EXAMPLE VI Phenol (94 g.) was dissolved in 40 percent formaldehyde solution (225 ml.) and the mixture cooled before adding sodium hydroxide (40 g.). The resulting solution was refluxed for five hours at 80 to 90C., after which it gelled to form a red resin. This material was cured at 80C. for 36 hours. Cured dried resin (150 g.) was ground and screened to a particle size of 30 100 US. mesh, and conditioned with alternate washings with solutions of 5 percent HCl and 5 percent NaOH.

The following Examples illustrate use of the resin in absorbing boron from solutions containing alkaline metal salts.

EXAMPLE VII An aqueous solution containing B IO p.p.m. as Na lLO Ca 100 p.p.m. as CaCl Na 2000 p.p.m. as Na SO was passed through a column containing the resin, prepared as described in Example VI. After passage of 140 bed-volumes of solution through the resin, 1.0 p.p.m. B was found in the effluent.

EXAMPLES VIII-XII Ex. No. Test Solution N0. of bed volumes" before l.0 p.p.m. B found in effluent 8 l0 p.p.m. B as Nat-A3 0, I

I00 p.p.m. Ca as CaCl 2000 p.p.m. Na as NaCl 9 l0 p.p.m. B as M1 8 0,

2000 p.p.m. Na as NzuSO 75 l0 l0 p.p.m. B as Na,B O

2000 p.p.m. Na as NaCl 34 l 1 l0 p.p.m. B as Na B O 100 p.p.m. Ca as CaCl, 42 l2 l0 p.p.m. B as Na B O l4 As demonstrated above, the resins are particularly effective for absorbing boron from solutions containing salts such as sodium sulfate and chloride, and especially calcium chloride.

Various changes and modifications of the invention can be made, and, to the extent that such variations incorporate the spirit of this invention, they are intended to be included within the scope of the appended claims.

What is claimed is:

l. The method of removing boron and arsenic anions from an aqueous solution having at least one of said anions dissolved therein which comprises contacting said aqueous solution with a cross-linked hydroxyaryl polymer having tetrahedral boron anion-receiving sites formed by polymerization of a pre-formed complex oi a hydroxyaryl compound and boron anion with a formaldehyde source and leaching the formed polymer with an acid which is effective in removing said boron anion and providing said boron anion-receiving sites.

2. The method according to claim 1 in which said aqueous solution contains inorganic salts in addition to said boron and arsenic compounds dissolved therein.

3. The method according to claim 2 in which said inorganic salt is selected from the sulfates and chlorides of sodium and calcium.

4. The method according to claim 2 in which said inorganic salt is calcium chloride.

S. The'method according to claim 1 in which said polymer is formed by reaction of salicylic acid, boric acid and formaldehyde in the presence of sodium hydroxide and then cross-linked with resorcinol.

6. The method according to claim 1 in which saic polymer is formed by reaction of gallic acid, boric acic and formaldehyde in the presence of sodium hydroxide and then cross-linked with resorcinol.

7. The method according to claim 1 in-which saic aqueous solution has a pH of at least 4.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,8873460 DATED 1 June 3, 1975 rwvmrorus; CHRISTOPHER JOHN WARD et a1.

It is CEIIiflEd that error appears rn 'he above-rdentified patent and that sard Letters Pateni are hereby corrected as shown below:

On Title Page, Column 1 after Related U.S. Application Data insert the following Foreign Application Priority Data Signed and Scaled this twenty-third of March I 976 June 8, 1972 United Kingdom October 26, 1972 United Kingdom [SEAL] Attesr:

RUTH C MASON Arresting Officer C. MARSHALL DANN ('nmmr'ssimn'r of Parenls and TYGt/(IHUIRS 

1. THE METHOD OF REMOVING BORON AND ARSENIC ANIONS FROM AN AQUEOUS SOLUTION HAVING AT LEAST ONE OF SAID ANIONS DISSOLVED THEREIN WHICH COMPRISES CONTACTING SAID AQUEOUS SOLUTION WITH A CROSS-LINKED HYDROXYARYL POLYMER HAVING TETRAHEDRAL BORON ANION-RECEIVING SITES FORMED BY POLYMERIZATION OF A PRE-FORMED COMPLEX OF A HYDROXYARYL COMPOUND AND BORON ANION WITH A FORMALDEHYDE SOURCE AND LEACHING THE FORMED POLYMER WITH AN ACID WHICH IS EFFECTIVE IN REMOVING SAID BORON ANION AND PROVIDING SAID BORON ANION-RECEIVING SITES.
 1. The method of removing boron and arsenic anions from an aqueous solution having at least one of said anions dissolved therein which comprises contacting said aqueous solution with a cross-linked hydroxyaryl polymer having tetrahedral boron anion-receiving sites formed by polymerization of a pre-formed complex of a hydroxyaryl compound and boron anion with a formaldehyde source and leaching the formed polymer with an acid which is effective in removing said boron anion and providing said boron anion-receiving sites.
 2. The method according to claim 1 in which said aqueous solution contains inorganic salts in addition to said boron and arsenic compounds dissolved therein.
 3. The method according to claim 2 in which said inorganic salt is selected from the sulfates and chlorides of sodium and calcium.
 4. The method according to claim 2 in which said inorganic salt is calcium chloride.
 5. The method according to claim 1 in which said polymer is formed by reaction of salicylic acid, boric acid and formaldehyde in the presence of sodium hydroxide and then cross-linked with resorcinol.
 6. The method according to claim 1 in which said polymer is formed by reaction of gallic acid, boric acid and formaldehyde in the presence of sodium hydroxide and then cross-linked with resorcinol. 